This disclosure relates to nanostructured materials, and in particular to nanostructured coatings and bulk materials, as well as methods for the manufacture thereof.
Nanostructured materials are those materials having average grain sizes smaller than about 100 nanometers. Such materials can have improved properties compared to those with larger grain sizes including improved abrasion resistance and wear resistance. For example, bulk tungsten carbide (WC/Co) materials with grain sizes in the nanometer range possess an abrasion resistance approximately double that of the most abrasion resistant conventional, i.e., microstructured, WC/Co material. The improved abrasion resistance has been attributed to the high hardness of the nanostructured material and their ultrafine grain sizes. The ultrafine grain size is thought to alter the fracture and material removal mechanisms. Nanostructured WC/Co bulk materials also exhibit better sliding wear resistance than their conventional counterparts. It has also been shown recently that nanostructured titanium dioxide (TiO2) bulk materials have wear resistance that is two to three times better than that exhibited by their conventional titanium dioxide counterparts.
Thermal spray techniques have been used to deposit thick, non-nanostructured oxide coatings, and there has been extensive experimental examination of the relationship between processing conditions and the phase constituents, structures and mechanical properties of such non-nanostructured coatings. Thermal spray techniques include air-plasma, electric are, flame spray and fuse, high velocity oxy-fuel, and detonation-gun spraying. However, relatively little is known of the relationship between processing techniques and the phase constituents, structures and mechanical properties of nanostructured coatings produced thereby. In view of the increasing importance of nanostructured materials, there remains a need for new nanostructured materials, as well as economical methods for the manufacture of such materials.